package com.hmdp.utils;

import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;

import java.util.Collections;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

// 利用的是setnx方法进行加锁，同时设hi好过期时间，防止死锁的情况出现
public class SimpleRedisLock implements ILock{

    private StringRedisTemplate redisTemplate;
    private String name; //锁的名称
    private static final String KEY_PREFIX="lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString() + "-";

    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }
    public SimpleRedisLock(String name,StringRedisTemplate redisTemplate) {
        this.redisTemplate = redisTemplate;
        this.name = name;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程标示
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        // 获取锁
        Boolean success = redisTemplate.opsForValue()
                .setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success);
    }

    @Override
    public void unlock(){
        // 调用lua脚本
        redisTemplate.execute(UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX+name),
                ID_PREFIX+Thread.currentThread().getId());
    }

    /*public void unlock() {
        // 获取线程标示
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        // 获取锁中的标示
        String id = redisTemplate.opsForValue().get(KEY_PREFIX + name);
        // 判断标示是否一致
        if(threadId.equals(id)) {
            // 释放锁
            redisTemplate.delete(KEY_PREFIX + name);
        }
    }*/
}
